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Topic: How are star gears machined?

Richard Fowler
Film God

Posts: 2392
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001

posted 09-21-2001 06:36 PM

Wil,
my key machine shop contractor, who has NASA and several major airlines for clients, was blown away on the quality of the Lavezzi parts we had modified by them for an O.E.M. account.....he asked for spare samples to show his staff what level of quality they should be going for.
Richard Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 09-21-2001 07:16 PM

Will,
The idea here is not to make just a few parts but to make hundreds in one run and keep all the tight tolerances. Making a few is easy, making hundreds at a run is far more difficult. I would urge you to attempt a tour at LaVezzi if you get to the Chicago area. You'll see what I mean.
I do have a 32 tooth Alumnium VKF sprocket blueprint I had drawn up(and also made)that I can send you if you want to tackle a hundred or so of them for me. My sprockets were made by Worral Grinding in Californis. They work great and have good tolerances. They only made six of them for my VV machine. Of course one thing you could do is to design and make 35/70m VKF sprockets for the Phillips DP-70. You'd actually sell bunches of thise so it would be a worthwhile project(venture)for you to tackle. I'd be first in line for several sets of them. Your target price cannot be over 250.00 List price per sprocket. My cost has to be at least 40% less than that.
Mark @ GTS

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Greg Mueller
Phenomenal Film Handler

Posts: 1687
From: Port Gamble, WA
Registered: Jun 99

posted 09-21-2001 08:17 PM

Wil
Probably a lot of what you're seeing in shop class are conservative "beginning" speeds, feeds and techniques. Once you get in to the real production world lots of things change. I have no doubt that lavezzi has been running these parts long enough and has pushed the envelope on production of each part to the point where they can manufacture each of them for a profit. I'm sure you'll be somewhat shocked by some of the things you'll see as you go along and get further from the class room and more into the competitive world of production. I had an instructor that although he taught us the numbers and formulas for material removal also made it very clear that these were only beginning points. Another instructor (not mine) would come out and yell at us if he saw us pushing the envelope. The difference was that my instructor was a successful machinist who was teaching during the great Boeing crash and the yelling instructor was never more than a teacher (I'm not dissing teachers). There's quite a difference between the class room and the competitive world of production machining, and you're right, you never quit learning.

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Greg Mueller
Amateur Astronomer, Machinist, Filmnut
http://www.muellersatomics.com/

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 09-22-2001 09:58 AM

An old phrase I once heard "when you quit learning you are dead"
Also Mark Twain waid "Never let your schooling interfere with your learning"

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Will Kutler
Phenomenal Film Handler

Posts: 1506
From: Tucson, AZ, USA
Registered: Feb 2001

posted 09-22-2001 12:51 PM

Hi everyone!

I guess you did not all read everything I wrote--yes, I do have a good amount of "real world" shop experience!

Now, Duh! CNC is for production--but duh! there was a time before CNC when duh--turret lathes, tracer mills, etc, etc were used for mass production! and yes, I have experience with both CNC and manual tools. Actually I love manual machining more than CNC!

So, duh, none of you really know me, or the type of work I am capable of, so send me a print of a star and cam! I'll see what I can do!

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 09-22-2001 01:19 PM

I also have quite a bit of machining experience, enough to make a star and cam or two but not hundreds at a time. Apparently you didn't read all of my posting either. Let me know when the first batch of new VKF style DP-70 sprockets are available. Will, also... you have to do your own drawings as I did for my 32 tooth Internittent sprocket(on autocad or what ever works for you). I still have enough of the 32 toothers left as the machine is still on it's first sprocket.
Mark @ GTS

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Will Kutler
Phenomenal Film Handler

Posts: 1506
From: Tucson, AZ, USA
Registered: Feb 2001

posted 09-22-2001 03:15 PM

So what is so difficult about mass production? There are special machine tools for this, and no, you don't need to rely on CNC! Unfortuantely, I do not have my own shop. Maybe I could make a Star and Cam in the college shop if I get permission. No, I do not have access to the special grinding machines needed to make sprockets! Yes, I am very experienced with Autocad, in fact I would like to purchase a computer for that purpose as I would love to get into photoetching--do you know what that is, Mark?

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Greg Mueller
Phenomenal Film Handler

Posts: 1687
From: Port Gamble, WA
Registered: Jun 99

posted 09-22-2001 04:41 PM

Wil
Quick, go start your own shop and put all of the stupid "duh" shops out of business. All you have to do is make a better product and sell it for cheaper than the competition. I have the equipment necessary to make just about anything on a projector, but I buy stuff from manufacturers who are already making the stuff. Why? Because they have already done all the R&D and all the leg work, made all the mistakes and know how to do it right. It is more cost effective (a term I'm sure you will become acquainted with in the near future) for me to do what I do and make money and buy the product of people who know what they're doing with their product, than it is to make one from scratch. Unless your time has absolutely no value, you simply cannot make a star gear (by hand) better and cheaper than one that is in production. Guess why turret lathes and tracer mills have been replaced by CNC equipment. As far as the difficlties of production go, guess you have to be there to appreciate that one. Good Luck in your new vocation.

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Greg Mueller
Amateur Astronomer, Machinist, Filmnut http://www.muellersatomics.com/

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 09-22-2001 04:46 PM

Photoetching is more accurately called chemical milling and is the basis of much precision work in not only printed crcuit board fabrication but other areas. Mark is well familiar with it as he has seen dimmer boards being etched in my shop from designs we did in Protel

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 09-22-2001 06:59 PM

Yes Will, I do. It is a process of making parts by masking and then etching away the unwanted areas of metal. In fact that is how printed circuit boards are made. I just got done etching a pair of boards for a class A line stage preamp for my home "high end" stereo system. Been making my own pcb's for years.
There are Photos of in the works audio projects at this site for those interested: http://albums.photopoint.com/j/AlbumIndex?u=51304&a=13785415&f=0

If you ever make PCB's be sure to get PCAD for doing this. Its the best PCB CAD program there is. You can download a free trial version at: http://www.pcad.com/downloads/utilities/p-cad2001/viewer2001/p-cad2001viewer.exe
Enjoy and have fun with it.
Mark @ GTS

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 09-22-2001 08:11 PM

Actually the old Dos Protel pack of Autotrax pcb and router and schematic schematic editor do up to 7 layer boards very nicely.
The latest Win version is very powerfull as it has a Spice module that also checks the finished board for possible induced signals
A freeware version is available called Easytrax from http://www.cia.com.au/rcsradio/index2.htm
as well they have the source code for writing your own drivers

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 09-23-2001 12:16 PM

Ok you PCB people you...I'm a proud user and supporter of Design Computation's DC/CAD...aka Draftsman-EE...it will out route just about any other router I've seen. It will do from 1 to 48 layers or so and around 8 common layers (aka planes). Too bad they went out of business but you tend to like what you are used to.

I'll stay out of this machinist bickering though.

Steve

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"Old projectionists never die, they just changeover!"

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 09-23-2001 12:29 PM

I tried HiWire 2 and found it the best router out there but was too expensive to buy Also they make a low end one called Smart Work

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Josh Jones
Redhat

Posts: 1207
From: Plano, TX
Registered: Apr 2000

posted 09-23-2001 12:54 PM

Your quite the photographer, Mark

That ferris wheel picture looks nice

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 09-23-2001 06:07 PM

Thanks for the compliment Josh. I've been taking pics since I was seven years old. I've pretty much retired my 35mm slr's for the larger format stuff. There is alot to photograph here in Utah and since I hike and do photos I might as well haul around the best I can afford to. I also do most of my own color darkroom work....time permitting. The ferris wheel picture is a digital shot taken at Lagoon and thats what I have been using for about 3 years now for general photos.
Mark 2 GTS

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